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    <a href="../index.html">cppreference.com</a> &gt; <a href=
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    free
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    Syntax:
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  <pre class="syntax-box">
  #include &lt;stdlib.h&gt;
  void free( void* ptr );
</pre>

  <p>The free() function deallocates the space pointed to by
  <em>ptr</em>, freeing it up for future use. <em>ptr</em> must have
  been used in a previous call to <a href="malloc.html">malloc</a>(),
  <a href="calloc.html">calloc</a>(), or <a href=
  "realloc.html">realloc</a>(). An example:</p>
  <pre class="example-code">
   typedef struct data_type {
     int age;
     char name[20];
   } data;              

   data *willy;
   willy = (data*) malloc( sizeof(*willy) );
   ...
   free( willy );               
</pre>

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    Related topics:
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    <a href="calloc.html">calloc</a><br>
    (C/C++ Keywords) <a href="../keywords/delete.html">delete</a><br>
    <a href="malloc.html">malloc</a><br>
    (C/C++ Keywords) <a href="../keywords/new.html">new</a><br>
    <a href="realloc.html">realloc</a>
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